Microamplification of specific chromosome sequences; an improved method for genome analysis.

An improved method was developed for microdissection and cloning of metaphase as well as pachytene chromosomes. The protocol incorporates efficient ligation of chromosomal DNA with linker adaptors, abolishment of microcloning steps and the reduction of micromanipulation. The threshold for amplifying genomic DNA template was in the range of 2-20 femtogram. The amplification products had a size distribution between 200 and 1300 bp (average 500 bp). Using pachytene chromosomes of maize the selectivity for segment-specific libraries can be increased between 10- and 20-fold. The approach described here is being applied to the fine mapping and isolation of genes conveying resistance against plant pathogens.